A parity-time (PT) symmetric sensor based on coherent perfect absorption laser (CPAL) for enhanced nuclear quadrupole resonance (NQR) signal detection

Abstract

The present invention discloses a parity-time (PT) symmetric sensor based on a coherent perfect absorption laser (CPAL) for enhancing nuclear quadrupole resonance (NQR) signal detection. The nuclear quadrupole resonance (NQR) signal detection system of the sensor is used to detect the nuclear quadrupole resonance (NQR) signal of the object to be measured multiple times and accumulate it as an excitation signal. The parity-time (PT) symmetric sensor system based on the coherent perfect absorption laser (CPAL) receives the excitation signal and its coherent signal and then obtains a detection signal to detect the category of the object to be measured. Since the center frequencies of the nuclear quadrupole resonance (NQR) signals of different substances have certain differences, and the parity-time (PT) symmetric sensor system based on the coherent perfect absorption laser (CPAL) will produce completely different outputs for excitation inputs of different frequencies, the present invention utilizes this characteristic and the high sensitivity of the coherent perfect absorption laser (CPAL) effect to effectively solve the problem that the electromagnetic signal energy is too low to be detected during the detection of explosives or drugs based on the nuclear quadrupole resonance (NQR) signal, thereby enhancing the sensitivity and accuracy of the detection.

Description

Technical Field

[0001] The present invention relates to a symmetric sensor and the field of nuclear quadrupole resonance (NQR) signal detection enhancement, and in particular to a parity-time (PT) symmetric sensor based on a coherent perfect absorption laser (CPAL) for enhancing nuclear quadrupole resonance (NQR) signal detection. Background Art

[0002] The physical mechanism of nuclear quadrupole resonance (NQR) is that atomic nuclei in a substance are exposed to an inhomogeneous electric field generated by the surrounding charge distribution. When this field exhibits an electric field gradient, the electric quadrupole moment of the nucleus couples with the gradient. This interaction causes the nuclear energy levels to split, forming a quantized energy state structure. At this point, if the energy quantum (hν) of the applied electromagnetic field exactly matches the energy difference between the nuclear energy levels, a resonance phenomenon occurs: the nucleus absorbs electromagnetic waves to transition from a lower energy state to a higher energy state, and the excited nucleus simultaneously returns to the ground state by emitting electromagnetic radiation of the same frequency. This electromagnetic transition between nuclear energy levels, independent of an external magnetic field, is called nuclear quadrupole resonance (NQR), and the electromagnetic signal at the corresponding frequency emitted by the excited nucleus is called the NQR signal. The spectral characteristics of NQR depend on the microstructure of the material itself. The applied electromagnetic field serves only to excite the resonance, and the resonance frequency is entirely determined by the coupling between the material's electric quadrupole moment and the electric field gradient. Even the same atomic nucleus will exhibit different nuclear quadrupole resonance (NQR) spectra in different molecules due to differences in local electric field gradients. Therefore, by measuring the resonance spectrum, it is not only possible to identify the nuclide species but also to infer the molecular structure, enabling non-destructive identification of substances. This molecule-specific NQR response offers unique advantages in fields such as chemical analysis, explosives detection, and drug identification.

[0003] A coherent perfect absorber laser (CPAL) point is observed in a parity-time (PT) symmetric system consisting of coupled gain and loss oscillators. Generally speaking, a CPA state represents a dark medium that completely absorbs incident radiation, while a laser state is a completely different concept, aiming to generate and propagate coherent electromagnetic radiation with zero linewidth. In the PT-symmetric CPAL point, by adjusting the initial phase difference between two counter-propagating monotonic input waves, it is possible to switch between the laser and CPA states, each with completely different scattering properties. This demonstrates the remarkable capability of PT-symmetric sensors based on CPALs to enhance sensitivity in the radio frequency range.

[0004] Nuclear quadrupole resonance (NQR) technology offers the advantages of high specificity, non-destructive testing, contactless operation, and the absence of radioactive or chemical contamination. However, its practical application faces significant challenges: 1. Weak signal: NQR relies on weak electromagnetic signals emitted by the substance being measured, which have low inherent strength, limiting detection sensitivity. 2. Low signal-to-noise ratio (SNR): Radio frequency interference (RFI), electromagnetic noise, and false signals from the instrument itself can severely interfere with NQR measurements, making it difficult to extract valid signals. 3. Difficulty in detection: Because the signal is susceptible to interference, advanced signal processing techniques and optimized detection methods are required to improve the SNR and achieve reliable detection. Summary of the Invention

[0005] To address the problems in the background art, the present invention provides a parity-time (PT) symmetric sensor based on a coherent perfect absorption laser (CPAL) for enhancing the detection of nuclear quadrupole resonance (NQR) signals. The present invention designs and manufactures a specific antenna for receiving nuclear quadrupole resonance (NQR) signals of a specific frequency. The CPAL-based PT symmetric sensor is used to enhance the accuracy and sensitivity of NQR signal detection.

[0006] The technical solution adopted in the present invention is:

[0007] The present invention provides a parity-time (PT) symmetric sensor based on a coherent perfect absorption laser (CPAL) for enhancing nuclear quadrupole resonance (NQR) signal detection, comprising:

[0008] The nuclear quadrupole resonance (NQR) signal detection system is used to detect the nuclear quadrupole resonance (NQR) signal of the object being measured multiple times and accumulate the NQR signal as an excitation signal.

[0009] A parity-time (PT) symmetric sensor system based on a coherent perfect absorption laser (CPAL) is used to receive an excitation signal and its coherent signal and then obtain a detection signal to detect the category of the object being measured.

[0010] The nuclear quadrupole resonance (NQR) signal detection system includes a computer, a radio frequency signal generator and receiver, a radio frequency power amplifier, a radio frequency switch, a preamplifier, and a radio frequency antenna. The object to be measured is placed at the center of the radio frequency antenna. The object to be measured and the radio frequency antenna are both located in an electromagnetic shielding environment. The radio frequency signal generator and receiver include a radio frequency signal generator and a radio frequency signal receiver. When the nuclear quadrupole resonance (NQR) signal detection system performs signal stimulation, the computer controls the radio frequency signal generator to generate a stimulation signal, which is then transmitted to the radio frequency antenna via the radio frequency power amplifier and the radio frequency switch in sequence, so that the center frequency of the radio frequency antenna is a preset center frequency. The radio frequency antenna receives the initial signal generated by the object to be measured, outputs the initial nuclear quadrupole resonance (NQR) signal after passing through the preamplifier, and the initial nuclear quadrupole resonance (NQR) signal is then transmitted to the computer via the radio frequency signal receiver for display. After multiple signal stimulations, each initial nuclear quadrupole resonance (NQR) signal is accumulated as an excitation signal and transmitted to a parity-time (PT) symmetric sensor system based on a coherent perfect absorption laser (CPAL).

[0011] The center frequency of the radio frequency antenna is approximately equal to the design frequency of the parity-time (PT) symmetric sensor system based on the coherent perfect absorption laser (CPAL), and is approximately equal to the center frequency of the nuclear quadrupole resonance (NQR) signal of the object being measured.

[0012] The radio frequency signal generator adopts an arbitrary waveform signal generator with a frequency range of 0-20 MHz.

[0013] The radio frequency antenna is a hollow solenoid coil and uses enameled wire.

[0014] The parity-time (PT) symmetric sensor system based on a coherent perfect absorption laser (CPAL) includes a first coupler, a first oscilloscope, a transmission line, a second coupler, a second oscilloscope, a loss element, and an amplifier element. The first coupler, the loss element, the transmission line, the amplifier element, and the second coupler are connected in sequence. The first coupler and the second coupler are connected to the first oscilloscope and the second oscilloscope, respectively. The excitation signal V1 and its coherent signal V2 are simultaneously transmitted to the parity-time (PT) symmetric sensor system based on a coherent perfect absorption laser (CPAL) composed of the loss element, the amplifier element, and the transmission line. After processing, the output first detection signal V3 and the second detection signal V4 are respectively transmitted to the first oscilloscope and the second oscilloscope through the first coupler and the second coupler for display.

[0015] The amplitude ratio of the excitation signal V1 and its coherent signal V2 is 2 1 / 2 / 2, the phase difference is 90 degrees.

[0016] The loss element has a positive conductance G, and the amplification element has a negative conductance -G.

[0017] The first coupler, the first oscilloscope, the transmission line, the second coupler, the second oscilloscope, the loss element and the transmission line between the amplifying element are all separated by an electrical length x, where x=π / 2+δx, and δx is a phase offset of the electrical length x.

[0018] The second detection signal V4 has an extreme value at the design frequency of the parity-time (PT) symmetric sensor system based on the coherent perfect absorption laser (CPAL), and it is detected that the current object being measured is an object category corresponding to the design frequency.

[0019] The parity-time (PT) symmetric sensor system based on coherent perfect absorption laser (CPAL) operates in the radio frequency domain and consists of a two-port equivalent transmission model. It adopts a monotonic sensing scheme by detecting whether the impedance perturbation at a given frequency is realized as a function of the output intensity.

[0020] The beneficial effects of the present invention are:

[0021] The present invention innovatively combines a nuclear quadrupole resonance (NQR) detection system and a parity-time (PT) symmetry sensor based on a coherent perfect absorption laser (CPAL). A specially designed antenna is used to input the nuclear quadrupole resonance (NQR) signal obtained by the nuclear quadrupole resonance (NQR) detection system as an excitation-maximizing input to the parity-time (PT) symmetry sensor based on a coherent perfect absorption laser (CPAL). The substance corresponding to the nuclear quadrupole resonance (NQR) signal is determined by judging the output of the parity-time (PT) symmetry sensor based on a coherent perfect absorption laser (CPAL).

[0022] Nuclear quadrupole resonance (NQR) detection relies on collecting electromagnetic signals emitted by the object being detected. However, the electromagnetic signals emitted by the material itself are relatively low in energy, making signal acquisition difficult. Furthermore, interference from factors such as radio frequency interference (RFI) and false positives can result in a low signal-to-noise ratio, making it difficult to extract useful signals. Parity-time (PT)-symmetric sensors based on coherent perfect absorption lasers (CPALs) have the remarkable ability to enhance sensitivity within the radio frequency range. The combination of these two technologies can effectively improve the sensitivity and accuracy of nuclear quadrupole resonance (NQR) detection of explosives, effectively resolving the issue of electromagnetic signals being too low in energy to be detected in explosives detection based on NQR signals.

[0023] Because the center frequencies of nuclear quadrupole resonance (NQR) signals of different substances vary, a parity-time (PT)-symmetric sensor system based on a coherent perfect absorption laser (CPAL) produces distinct outputs for excitation inputs of different frequencies. The present invention utilizes this characteristic and the high sensitivity of the CPAL effect to effectively address the problem of electromagnetic signal energy being too low to be detected during explosives or drug detection based on nuclear quadrupole resonance (NQR) signals, thereby enhancing detection sensitivity and accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Schematic diagram of the combination of a two-port equivalent transmission line model of a parity-time (PT) symmetric sensor based on a coherent perfect absorption laser (CPAL) and a nuclear quadrupole resonance (NQR) signal according to the present invention;

[0025] Figure 2 Schematic diagram of a nuclear quadrupole resonance (NQR) signal detection system of the present invention;

[0026] Figure 3 Schematic diagram of the principle of excitation and generation of nuclear quadrupole resonance (NQR) signals of the detected substance;

[0027] Figure 4 Schematic diagram of the design of the radio frequency antenna of the present invention;

[0028] Figure 5 is a spectrum diagram of the processed nuclear quadrupole resonance (NQR) signal of the present invention;

[0029] Figure 6 Schematic diagram of a parity-time (PT) symmetric sensor system based on a coherent perfect absorption laser (CPAL) in the radio frequency (RF) domain according to the present invention;

[0030] Figure 7 Schematic diagram of a T-type equivalent circuit used in the transmission line of the present invention;

[0031] Figure 8 A schematic diagram of the relationship between sensor output and input frequency when using the transmission line model of the present invention;

[0032] Figure 9 This is a schematic diagram of the relationship between sensor output and input frequency when using the T-type equivalent circuit model of the present invention;

[0033] In the figure: 11. First coupler, 12. First oscilloscope, 13. Transmission line, 14. Second coupler, 15. Second oscilloscope, 16. Loss element, 17. Amplification element, 21. Computer, 22. RF signal generator and receiver, 23. RF power amplifier, 24. RF switch, 25. Preamplifier, 26. RF antenna, 27. Electromagnetic shielding environment. DETAILED DESCRIPTION

[0034] Exemplary embodiments are described in detail herein, with examples illustrated in the accompanying drawings. When the following description refers to the drawings, identical numerals in different drawings represent identical or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments are not intended to represent all embodiments consistent with this application.

[0035] The terms used in this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The singular forms "a," "the," and "the" used in this application are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term "and / or" as used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0036] It should be understood that although the terms first, second, third, etc. may be used in this application to describe various information, such information should not be limited to these terms. These terms are only used to distinguish information of the same type from each other. For example, without departing from the scope of this application, first information may also be referred to as second information, and similarly, second information may also be referred to as first information. Depending on the context, the word "if" as used herein may be interpreted as "at the time of" or "when" or "in response to determining".

[0037] Specific embodiments are given below to introduce the technical solutions of the present application in detail.

[0038] The present invention discloses a parity-time (PT) symmetry sensor based on a coherent perfect absorption laser (CPAL) for enhancing nuclear quadrupole resonance (NQR) signal detection, comprising a nuclear quadrupole resonance (NQR) signal detection system and a parity-time (PT) symmetry sensor system based on a coherent perfect absorption laser (CPAL). The nuclear quadrupole resonance (NQR) signal detection system is used to detect the nuclear quadrupole resonance (NQR) signals of a measured object multiple times and accumulate them as an excitation signal; the parity-time (PT) symmetry sensor system based on a coherent perfect absorption laser (CPAL) is used to receive the excitation signal and its coherent signal to obtain a detection signal, thereby detecting the type of the measured object.

[0039] The object to be measured in the present invention is 500g of the nitrogen-containing compound sodium nitrite. The experimental data verify that the center frequency of its nuclear quadrupole resonance (NQR) is approximately 4.6-4.8MHz. 14 The center frequency may vary due to factors such as different N abundance. The center frequency of the sodium nitrite used in the present invention is approximately 4.6 MHz. This range is given based on rigor, and the safety of the drug is better than that of other nitrogen-containing explosives. The nitrogen-containing compound sodium nitrite is placed in a plastic box for testing.

[0040] like Figure 2 As shown in FIG, the nuclear quadrupole resonance (NQR) signal detection system includes a computer 21, a radio frequency signal generator and receiver 22, a radio frequency power amplifier 23, a radio frequency switch 24, a preamplifier 25 and a radio frequency antenna 26. The radio frequency antenna 26 is a hollow solenoid coil and uses enameled wire. The object to be measured is placed at the center of the radio frequency antenna 26. The object to be measured and the radio frequency antenna 26 are both located in an electromagnetic shielding environment 27. Figure 4As shown, the radio frequency antenna 26 of the present invention can be a hollow solenoid coil of copper tube and enameled wire. The entire coil diameter is 11 cm, the length is 17 cm, and the pitch is 10 mm, so that it can completely wrap the object being measured. The radio frequency signal generator and receiver 22 includes a radio frequency signal generator and a radio frequency signal receiver. The radio frequency signal generator uses an arbitrary waveform signal generator with a frequency range of 0-20 MHz and can be controlled by a host computer PC. The output frequency accuracy can reach 10 -6 Order of magnitude.

[0041] The workflow of the nuclear quadrupole resonance (NQR) signal detection system consists of two phases: excitation and reception. In the excitation process, computer 1 sets the parameters of the RF pulse and controls an arbitrary waveform RF signal generator to synthesize the excitation signal. The excitation signal is amplified by a power amplifier and then switched to transmit mode by RF switch 24. The amplified pulse is radiated by RF antenna 26 in an electromagnetically shielded environment 27, exciting the object under test to produce a nuclear quadrupole resonance (NQR) signal. In the reception process, the weak NQR signal emitted by the object under test, which is also reflected by RF antenna 26, is initially amplified by a preamplifier to reduce the impact of subsequent processing noise. The signal is then received by an RF signal receiver and ultimately transmitted to computer 1 for filtering and other processing. The power amplifier has a maximum output power of 20W, a maximum output amplitude of 28Vpp, a maximum output current of 1A, a voltage gain that can be doubled or quadrupled, and a signal input bandwidth of DC to 5MHz. The preamplifier has a bandwidth of 20kHz to 3000MHz, a gain of 32dB, and a noise figure of 2.5dB. When the nuclear quadrupole resonance (NQR) signal detection system performs signal stimulation, the computer 21 controls the radio frequency signal generator to generate a stimulation signal, which is then transmitted to the radio frequency antenna 26 through the radio frequency power amplifier 23 and the radio frequency switch 24 in sequence, so that the center frequency of the radio frequency antenna 26 is a preset center frequency. The center frequency of the radio frequency antenna 26 is approximately equal to the design frequency of the parity-time (PT) symmetric sensor system based on the coherent perfect absorption laser (CPAL), and is approximately equal to the center frequency of the nuclear quadrupole resonance (NQR) signal of the object being measured. In specific implementation, the radio frequency antenna 26 is designed to have an inductance of 3μH and an internal resistance of 0.3Ω, so that its center frequency is approximately 4.6MHz, that is, near the design frequency. Figure 5 As shown; the radio frequency antenna 26 receives the initial signal generated by the object under test and outputs the initial nuclear quadrupole resonance (NQR) signal after passing through the preamplifier 25. The initial nuclear quadrupole resonance (NQR) signal is then transmitted to the computer 21 for display via the radio frequency signal receiver. After multiple signal stimulations, each initial nuclear quadrupole resonance (NQR) signal is accumulated as an excitation signal and transmitted to a parity-time (PT) symmetric sensor system based on a coherent perfect absorption laser (CPAL).

[0042] like Figure 3 As shown in the figure, the excitation and generation process of the nuclear quadrupole resonance (NQR) signal is shown. For an atom, when an electromagnetic signal with certain conditions is applied externally, and the frequency of the electromagnetic signal (hv multiplied by the Planck constant) satisfies the energy level difference △E of the nuclear transition, the nucleus can absorb its electromagnetic energy and produce a transition, from the equilibrium state to the excited state. After the electromagnetic wave ends, the transitioned nucleus will release an electromagnetic signal in the process of returning to the equilibrium state due to instability. This signal is the nuclear quadrupole resonance (NQR) signal.

[0043] like Figure 6 As shown in the figure, the received nuclear quadrupole resonance (NQR) signal is processed by low-noise preamplification, cumulative sampling, filtering, etc., and then roughly converted into the spectrum diagram shown in the figure through Fast Fourier Transform (FFT). In order to simplify the experimental process and eliminate unnecessary interference, an arbitrary waveform generator (AWG) can be directly used to generate two similar coherent signals with a frequency of 4.6 MHz, which are used as input waves of the two ports of the parity-time (PT) symmetric sensor system based on coherent perfect absorption laser (CPAL).

[0044] like Figure 1 As shown, a parity-time (PT) symmetric sensor system based on a coherent perfect absorption laser (CPAL) includes a first coupler 11, a first oscilloscope 12, a transmission line 13, a second coupler 14, a second oscilloscope 15, a loss element 16, and an amplifier 17. The first coupler 11, loss element 16, transmission line 13, amplifier 17, and second coupler 14 are connected in sequence. The loss element 16 has a positive conductance G and can be a resistor or a capacitor. The amplifier 17 has a negative conductance -G and is a negative impedance converter (NIC) with a negative conductance -G. The transmission lines between the first coupler 11, first oscilloscope 12, transmission line 13, second coupler 14, second oscilloscope 15, loss element 16, and amplifier 17 are separated by an electrical length x, where x = π / 2 + δx, where δx is the phase offset of the electrical length x.

[0045] The first coupler 11 and the second coupler 14 are connected to the first oscilloscope 12 and the second oscilloscope 15 respectively, and the excitation signal V1 and its coherent signal V2 are simultaneously transmitted to the parity-time (PT) symmetric sensor system based on the coherent perfect absorption laser (CPAL) composed of the loss element 16, the amplifier element 17 and the transmission line 13. After processing, the output first detection signal V3 and the second detection signal V4 are transmitted to the first oscilloscope 12 and the second oscilloscope 15 respectively through the first coupler 11 and the second coupler 14 for display. Among them, the amplitude ratio of the excitation signal V1 and its coherent signal V2 is 2 1 / 2 / 2, with a phase difference of 90 degrees. If the second detection signal V4 reaches an extreme value at the design frequency of the parity-time (PT) symmetric sensor system based on a coherent perfect absorption laser (CPAL), the current object being measured is detected as belonging to the object category corresponding to the design frequency. The parity-time (PT) symmetric sensor system based on a coherent perfect absorption laser (CPAL) operates in the RF domain and consists of a two-port equivalent transmission model. It employs a monotonic sensing scheme, detecting whether impedance perturbations at a given frequency are present as a function of output intensity.

[0046] like Figure 7 Figure 1 shows the T-type equivalent circuit used for the transmission line in the parity-time (PT) symmetric sensor system based on a coherent perfect absorption laser (CPAL) according to the present invention. The CPAL-based parity-time (PT) symmetric sensor system consists of a loss element 16 with a conductance G and an amplification element 17 with an effective negative conductance -G. These gain and loss elements are separated by an electrical length x = π / 2 + δx, which can be achieved by a transmission line or a compact T-type equivalent circuit. The system operates at a set frequency of 4.6 MHz, and thus can be calculated according to the following formula:

[0047] C 1= Y 0 / ( ω 0sinx)

[0048] L 1= L 2=sinx / ( Y 0 ω 0(1–cosx))

[0049] in, C 1 is the capacitor, C 1=684.84pF; Y 0 is the intermediate parameter, G / Y0=2 1 / 2 ; ω 0 is the middle frequency, ω 0= f / 2π, f is the design frequency;L 1 and L 2 is the first and second inductors, L 1= L 2=1712.09nH.

[0050] In addition, the pseudo-tensor R p Used to simulate impedance changes in sensing or driving elements; the transmission line is designed for a frequency of 4.6MHz.

[0051] The Coherent Perfect Absorption Laser (CPAL) point is a self-coupling spectral singularity of a parity-time (PT) symmetric system, at which the laser state and the Coherent Perfect Absorption CPA state (which can be regarded as a time-reversed laser) can coexist at a given wavelength (the so-called Coherent Perfect Absorption Laser (CPAL) point). The peak voltages of the excitation signal V1 and its coherent signal V2 of the present invention are 2.42 and 1, respectively. The coherent nuclear quadrupole resonance (NQR) signal is input into the sensor system, and the circuit simulation is performed using the Advanced Design System (ADS). In the Advanced Design System (ADS), the peak voltages of the excitation signal V1 and its coherent signal V2 ... peak voltages of the coherent nuclear quadrupole resonance (NQR) signal are input into the sensor system, and the circuit simulation is performed using the Advanced Design System (ADS). In the Advanced Design System (ADS), the peak voltages of the excitation signal V1 and the coherent signal V2 are 2.42 and 1, respectively. The peak voltages of the coherent nuclear quadrupole resonance (NQR) signal are 2.42 and 1, respectively. The peak voltages of the coherent nuclear quadrupole resonance (NQR) signal are 2.42 and 1, respectively. The peak voltages of the coherent nuclear quadrupole resonance (NQR) signal are 2.42 and 1, respectively. The peak voltages of the coherent nuclear quadrupole resonance (NQR) signal are 2.42 and 1, respectively. The peak voltages of the coherent nuclear quadrupole resonance (N Figure 1 The model shown in FIG. 1 is used for AC simulation to obtain the frequency spectrum of the first detection signal V3 and the second detection signal V4, as shown in FIG. Figure 8 As shown in the figure, the X-axis of the spectrum diagram represents the frequency of the coherent signal input at both ends of the system. Since the values ​​of the first detection signal V3 and the second detection signal V4 are both zero when there is no input signal at the two end ports, when the input signal frequency is consistent with the set frequency, the signal amplitude reaches an extreme value, which produces a very large contrast compared to the input signal of non-set frequency, thereby improving the sensitivity of nuclear quadrupole resonance (NQR) signal detection to a certain extent. The actual implementation of this system in the radio frequency range can be achieved by using an equivalent circuit instead of a transmission line model, such as Figure 7 As shown, the above simulation is repeated using an equivalent circuit to obtain the frequency spectrum of the first detection signal V3 and the second detection signal V4, as shown in FIG. Figure 9 As shown in the figure, after analysis, the error is within the acceptable range.

[0052] The embodiments described above are merely descriptions of preferred implementations of the present invention and are not intended to limit the scope of the invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should fall within the scope of protection determined by the claims of the present invention.

Claims

1. A parity-time (PT) symmetric sensor based on a coherent perfect absorption laser (CPAL) for enhancing nuclear quadrupole resonance (NQR) signal detection, characterized in that: include: A nuclear quadrupole resonance (NQR) signal detection system is used to detect the nuclear quadrupole resonance (NQR) signal of the object being measured multiple times and accumulate it as an excitation signal; A parity-time (PT) symmetric sensor system based on a coherent perfect absorption laser (CPAL) is used to receive the excitation signal and its coherent signal to obtain a detection signal. When the detection signal has an extreme value at the design frequency of the parity-time (PT) symmetric sensor based on a coherent perfect absorption laser (CPAL), it is detected that the current object being measured belongs to the object category corresponding to the design frequency.

2. The parity-time (PT) symmetric sensor based on a coherent perfect absorption laser (CPAL) for enhancing nuclear quadrupole resonance (NQR) signal detection according to claim 1, characterized in that: The nuclear quadrupole resonance (NQR) signal detection system comprises a computer (21), a radio frequency signal generator and receiver (22), a radio frequency power amplifier (23), a radio frequency switch (24), a preamplifier (25) and a radio frequency antenna (26). The object to be measured is placed at the center of the radio frequency antenna (26). The object to be measured and the radio frequency antenna (26) are both located in an electromagnetic shielding environment (27). The radio frequency signal generator and receiver (22) comprise a radio frequency signal generator and a radio frequency signal receiver. When the nuclear quadrupole resonance (NQR) signal detection system performs signal stimulation, the computer (21) controls the radio frequency signal generator to generate a stimulation signal, which is then sequentially transmitted through the radio frequency power amplifier (23). The radio frequency amplifier (23) and the radio frequency switch (24) transmit the signal to the radio frequency antenna (26), so that the center frequency of the radio frequency antenna (26) is a preset center frequency. The radio frequency antenna (26) receives the initial signal generated by the object to be measured and outputs the initial nuclear quadrupole resonance (NQR) signal after passing through the preamplifier (25). The initial nuclear quadrupole resonance (NQR) signal is then transmitted to the computer (21) for display via the radio frequency signal receiver. After multiple signal stimulations, each initial nuclear quadrupole resonance (NQR) signal is accumulated as an excitation signal and transmitted to a parity-time (PT) symmetric sensor system based on a coherent perfect absorption laser (CPAL).

3. The parity-time (PT) symmetric sensor based on a coherent perfect absorption laser (CPAL) for enhancing nuclear quadrupole resonance (NQR) signal detection according to claim 2, characterized in that: The preset center frequency of the radio frequency antenna (26) is equal to the design frequency of the parity-time (PT) symmetric sensor system based on the coherent perfect absorption laser (CPAL).

4. The parity-time (PT) symmetric sensor based on a coherent perfect absorption laser (CPAL) for enhancing nuclear quadrupole resonance (NQR) signal detection according to claim 2, characterized in that: The radio frequency signal generator adopts an arbitrary waveform signal generator with a frequency range of 0-20 MHz.

5. The parity-time (PT) symmetric sensor based on coherent perfect absorption laser (CPAL) for enhancing nuclear quadrupole resonance (NQR) signal detection according to claim 2, characterized in that: The radio frequency antenna (26) is a hollow solenoid coil and uses enameled wire.

6. The parity-time (PT) symmetric sensor based on coherent perfect absorption laser (CPAL) for enhancing nuclear quadrupole resonance (NQR) signal detection according to claim 1, characterized in that: The parity-time (PT) symmetric sensor system based on a coherent perfect absorption laser (CPAL) comprises a first coupler (11), a first oscilloscope (12), a transmission line (13), a second coupler (14), a second oscilloscope (15), a loss element (16) and an amplifier element (17). The first coupler (11), the loss element (16), the transmission line (13), the amplifier element (17) and the second coupler (14) are connected in sequence. The first coupler (11) and the second coupler (14) are respectively connected to the first oscilloscope (12) and the second oscilloscope (15). After the excitation signal V1 and the coherent signal V2 are simultaneously transmitted to the loss element (16), the amplifier element (17) and the transmission line (13) for processing, the output first detection signal V3 and the second detection signal V4 are respectively transmitted to the first oscilloscope (12) and the second oscilloscope (15) through the first coupler (11) and the second coupler (14) for display.

7. The parity-time (PT) symmetric sensor based on coherent perfect absorption laser (CPAL) for enhancing nuclear quadrupole resonance (NQR) signal detection according to claim 6, characterized in that: The amplitude ratio of the excitation signal V1 and its coherent signal V2 is 2 1 / 2 / 2, the phase difference is 90 degrees.

8. The parity-time (PT) symmetric sensor based on coherent perfect absorption laser (CPAL) for enhancing nuclear quadrupole resonance (NQR) signal detection according to claim 6, characterized in that: The loss element (16) has a positive conductance G, and the amplification element (17) has a negative conductance -G.

9. The parity-time (PT) symmetric sensor based on coherent perfect absorption laser (CPAL) for enhancing nuclear quadrupole resonance (NQR) signal detection according to claim 6, characterized in that: The first coupler (11), the first oscilloscope (12), the transmission line (13), the second coupler (14), the second oscilloscope (15), the loss element (16), and the transmission line between the amplifying element (17) are all separated by an electrical length x, where x=π / 2+δx, and δx is a phase offset of the electrical length x.

10. The parity-time (PT) symmetric sensor based on coherent perfect absorption laser (CPAL) for enhancing nuclear quadrupole resonance (NQR) signal detection according to claim 6, characterized in that: The second detection signal V4 has an extreme value at the design frequency of the parity-time (PT) symmetric sensor system based on the coherent perfect absorption laser (CPAL), and it is detected that the current object being measured is an object category corresponding to the design frequency.

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